Event Notification Report for April 10, 2008

FAILED DETECTOR HEADS

"At 1903 CST, on 04-10-08 the Plant Shift Superintendent (PSS) was notified that an alarm was received in the C-335 Area Control Room for the C-335 Unit 2 Cell 7 UF6 Release Detection (PGLD) System. Operators responded to the local panel and found all detector heads in alarm. Operators attempted to reset the system and the system would not reset, all heads remained in alarm. Operators then responded to the Unit 2 Cell 7 cell floor with the proper PPE and confirmed there was not a UF6 release. This PGLD System contains detectors that cover the C-335 Unit 2 Cell 7 cell housing roof and cell exhaust duct and sections 3 & 4 of the cell bypass housing. At the time of this alarm, C-335 Unit 2 Cell 7 and sections 3 & 4 of the cell bypass were operating above atmospheric pressure. TSR 2.4.4.1 requires that at least the minimum number of detector heads in the cell housing roof, cell exhaust duct, and cell bypass housing are operable during steady state operations above atmospheric pressure. With all the Unit 2 Cell 7 PGLD system heads locked in alarm, none of the required 3 heads in the cell housing roof and cell exhaust duct were operable and less of the required 3 heads in the cell bypass housing sections were operable. This PGLD System was declared inoperable, TSR LCOs 2.4.4.1.A.1 and 2.4.4.1.C.1 were entered and a continuous smoke watch was put in place within one hour. An investigation is ongoing to attempt to determine the cause of the failure. This event is being reported as a 24 hour event in accordance with 10CFR 76.120(c)(2)(i). This is an event in which equipment is disabled or fails to function as designed when: a.) the equipment is required by a TSR to prevent releases, prevent exposures to radiation and radioactive materials exceeding specified limits, mitigate the consequences of an accident, or restore this facility to a pre-established safe condition after an accident; b.) the equipment is required by a TSR to be available and operable and either should have been operating or should have operated on demand, and c.) no redundant equipment is available and operable to perform the required safety function.

"The NRC Resident Inspector has been notified of this event.

"PGDP Assessment and Tracking Report No. ATRC-08-1089; PGDP Event Report No. PAD-2008-10; Worksheet No. 44134 Responsible Division: Operations"

* * * UPDATE FROM B. WALLACE TO J. KNOKE AT 1021 EDT ON 6/4/08 * * *

The update is a retraction. Investigation has attributed the false alarm to a moisture problem and not a loss of power. The system did not fail.

The licensee notified the NRC Resident Inspector. Notified R2 (Robert Haag) and NMSS (Jack Guttmann)

"ANALYSIS INDICATES CONTAINMENT COOLERS MAY NOT HAVE AUTOMATICALLY STARTED IN SLOW SPEED FOLLOWING POSTULATED MAIN STEAM LINE BREAK"

"Information provided by another plant identified a condition where Containment Fan Coolers may trip if running in fast speed and not start automatically in slow speed, following a Loss of Coolant (LOCA) or Main Steam Line Break (MSLB). Wolf Creek commenced evaluation to determine if our Containment Coolers were susceptible to this condition.

"Investigation and analysis as of this date indicate that in the case of a Main Steam Line Break, the coolers could trip while running in fast speed and not be able to be automatically started by the sequencer in slow speed due to present electrical design configuration. The peak containment pressure in this case would exceed the analysis of record by approximately 5 psig.

"For the spectrum of the smaller break LOCA's, where actuation is delayed until pressurizer low pressure Safety Injection or the Containment Hi 1 pressure signal, analysis shows that the Containment Pressures would not be exceeded if the Containment Fan Coolers did not automatically start in slow speed. For a Large Break LOCA, analysis shows that the Containment Cooler Fans would be shed prior to tripping, and would be automatically started in slow speed by the sequencer.

"Wolf Creek is currently in a defueled condition, for Refueling Outage 16. Continued evaluation and analysis of this issue is ongoing. This issue will be resolved prior to the plant entering Mode 4, where Technical Specification 3.6.6 requires Containment Fan Coolers be operable."

The information was originally received from Callaway.

The licensee notified the NRC Resident Inspector.

* * * UPDATE AT 1245EDT ON 06/20/08 FROM LANCE LANE TO S. SANDIN * * *

The licensee is retracting this event based on the following:

"Wolf Creek evaluated this concern and concluded that the condition did not exist at Wolf Creek. Further analysis of the Main Steam Line Break, if this concern had existed, showed that the calculated post-accident pressure and temperature peak values would not exceed the peak accident values in the Final Safety Analysis Report. Therefore, an unanalyzed condition did not exist and Wolf Creek is retracting the 50.72(b)(3)(ii)(B) notification."

The licensee informed the NRC Resident Inspector. Notified R4DO (Farnholtz).

FITNESS FOR DUTY NON-LICENSED SUPERVISOR

"A non-licensed employee supervisor had a confirmed positive for alcohol during a for cause fitness for duty test. The employees access to the plant has been terminated."

Contact the HOO for additional details.

The licensee will notify the NRC Resident Inspector.